1. Field of the Invention
The present invention relates to a dummy employed for a dynamic test on a car crash, and more specifically, it relates to the structure of a neonate dummy.
2. Description of the Background Art
The new Japanese Road Traffic Act coming into force in Apr. 2000 obligates a car driver to employ a neonate safety seat for an automobile (hereinafter simply referred to as a child seat) for a child, including a neonate, under the age of six. According to JIS and standards provided by ECE, FMVSS and the Ministry of Land, Infrastructure and Transport, child seats are classified into several types in response to the weights of children along with standards for a neonate. In these standards, a dynamic test is provided with reference to head-on and rear-end car crashes, and a dummy employed for such a dynamic test is specified for each type of the child seat.
A dummy (hereinafter referred to as a TNO PO dummy) of a Dutch research organization is specified for the dynamic test on a child seat for a neonate. This TNO PO dummy is set to 3400 g in mass, and has an integral body structure.
The structure of the body of a neonate is now discussed. According to the World Health Organization (WHO), a neonate born after at least 37 gestational weeks with a birth weight of at least 2500 g is called a normally born neonate. Therefore, it is assumed that the term xe2x80x9cneonatexe2x80x9d employed in this specification indicates the normally born neonate defined by WHO.
The body of a neonate is not a miniature of an adult body. The structure and functions of the neonatal body are so premature that an accident may more seriously influence the neonatal body as compared with an adult body. The skeleton and functions of the neonatal body develop to degrees close to those of the adult body conceivably at the age of about twelve. Therefore, the characteristics of the neonatal body must be taken into due consideration.
(1) Head of Neonate
A neonate has a big head, occupying about 30% of the total weight, and a flabby neck. Consequently, the head of the neonate is readily shaken when receiving an impact. The thin scalp of the neonate has weak cushioning properties for protecting the skull, which is thin and flabby with thin and fragile dura mater. The facial bones are small as compared with the skull. Consequently, the head is more readily affected than the face. Cerebral vessels (pontine veins) are so thin and fragile by nature that the neonate readily bleeds when strongly shaken.
(2) Cervical Vertebrae of Neonate
The neonate has a big head and a flabby neck. When an impact is applied to the head, therefore, a large load is applied to the cervical vertebrae forming the neck. The centra (vertebrae) forming the cervical vertebrae, the ligaments forming the basivertebral joints connecting the same and muscles are undeveloped. The degree of freedom in movement of the cervical vertebrae is so large that particularly a baby under the age of one hardly has resistance against external force. The cervical vertebrae are so elastic and dilatable that the same are readily dislocated or fractured when excessively bent or expanded. Therefore, compression or ablation on cervical medullae in the cervical vertebrae may result in a critical damage. In the neonatal body, regions located on high positions of the cervical vertebrae are particularly readily damaged as compared with the adult body.
Thus, it is extremely important to protect the brain and the cervical vertebrae of the neonate so that the head does not collide with a hard substance and the neck is not excessively elongated or shaken when an impact is applied particularly to the head of the neonate.
In the current dynamic test, the behavior of the head part, the thoracic part and the abdominal part of the aforementioned TNO PO dummy following a car crash and the values of affection on these regions can be recognized to some extent. However, all regions of the body of the TNO PO dummy are integrated and hence the behavior of the head part, the thoracic part and the abdominal part and the values of affection on these regions cannot be correctly recognized. Further, the behavior of the cervical vertebrae regarded as particularly important and the value of affection thereon cannot be recognized. This is because the TNO PO dummy having an integral structure cannot correctly replicate the structure of a neonatal body having a flabby neck.
Accordingly, the present invention has been proposed in order to solve the aforementioned problems, and an object thereof is to develop a neonate dummy enabling grasp of a movement of the head of a neonate, the values of impacts applied to the thoracic part and the abdominal part (including the lumbar part) and the value of affection on the cervical vertebrae as well as clarification of the mechanism of cervical disorder resulting from an impact.
In order to attain the aforementioned object, the neonate dummy, employed for a dynamic test, according to the present invention comprises a head part and a body part including a neck part coupled with the aforementioned head part, while the aforementioned head part and the aforementioned body part are separated from each other, i.e. not integrally connected, due to the interposed neck part.
The head part and the body part are separated from each other so that the head part behaves equally to the head of an actual neonate in the dynamic test, whereby a movement of the head of the neonate and the value of affection applied to the head can be correctly grasped.
According to the present invention, the aforementioned body part preferably includes a bar member corresponding to the backbone of a neonate, for forming the aforementioned neck part on an upper region of the aforementioned bar member. According to this structure, the neonate dummy replicates the skeleton of a neonate so that the head part and the neck part behave equally to the head and the neck of an actual neonate in the dynamic test, whereby movements of the head part and the neck part as well as the values of affection applied to the head part and the neck part can be correctly grasped.
According to the present invention, the aforementioned head part is preferably pivotally coupled to the aforementioned neck part to be anteroposteriorly rotatable. According to the present invention, further, the aforementioned head part is preferably pivotally coupled to the aforementioned neck part to be laterally rotatable. According to this structure, the neonatal dummy more correctly replicates the skeleton of a neonate so that the head part and the neck part behave more equally to the head and the neck of an actual neonate in the dynamic test, whereby movements of the head part and the neck part as well as the values of affection applied to the head part and the neck part can be more correctly grasped.
According to the present invention, acceleration sensors are preferably provided on positions corresponding to the upper and lower ends of the cervical vertebrae of a neonate respectively. Thus, the amount of shear of the cervical vertebrae of the neonate can be measured in the dynamic test, for correctly grasping a movement of the neck part and the value of affection applied to the neck part. Consequently, the mechanism of cervical disorder resulting from an impact can be clarified.
According to the present invention, the aforementioned body part preferably includes a thoracic part and a lumbar part, and acceleration sensors are preferably provided on the centroidal position of the aforementioned head part, the centroidal position of the aforementioned thoracic part and the centroidal position of the aforementioned lumbar part respectively. Thus, movements of the head part and the neck part as well as the values of affection applied to the head part and the neck part can be more correctly grasped in the dynamic test.
According to the present invention, the aforementioned body part preferably includes arm parts and leg parts, and joints moving similarly to those of the body of a neonate are provided on the aforementioned arm parts and the aforementioned leg parts respectively. Thus, behavior of the body of a neonate can be correctly grasped in the dynamic test.